Two Categories of Arguments

ReasoningPreviously we discussed how to identify and evaluate arguments. Recall that Philosophy’s primary method is pursuing reason found in argumentation.

Now, let’s look at two categories of arguments.

There are two categories of arguments that I want you to be able to identify and explain: deductive and inductive arguments.

In a deductive argument, if the argument is valid and if you accept the supporting reasons (aka premises) as true, then you must necessarily accept the conclusion as true.

Here’s a typical example:

Premise: All men are mortal.
Premise: Dr. Boshears is a man.
Conclusion: Therefore, Dr. Boshears is mortal.

With an inductive argument we reason from premises to a conclusion that is supported by the premises, but the conclusion does not necessarily follow from the premises.

With inductive reasoning we have conclusions that are probable, but not certain.

To illustrate this point, consider the following examples:

  • The solar system is probably the result of an enormous explosion—a “big bang”—that occured billions of years ago.
  • On the average, a person with a college degree will earn over $1,340,000 more in his or her lifetime than a person with just a high school diploma.

The “big bang” example here demonstrates what we call causal reasoning which is a kind of inductive reasoning in which one event is claimed to be the results of the occurrence of another event.

Causal reasoning is a basic pattern of thinking that we use to organize and make sense of the way we experience the world.

In the lifetime earnings example we have what is called an empirical generalization which is a kind of inductive reasoning in which a general statement is made about an entire group based on observing some members of the group.

Empirical generalizations are a bit more advanced and more susceptible to error than causal reasoning. This is because empirical generalizations are reason from limited samples to arrive at conclusions about broad populations. In order for this kind of reasoning to avoid slipping off the rails, the sample being used to draw conclusions needs to be properly representative of the population. There are a variety of methods that researchers can use to ensure that an adequate sample is gathered.